// 第一類
public void drawText (String text, float x, float y, Paint paint)
public void drawText (String text, int start, int end, float x, float y, Paint paint)
public void drawText (CharSequence text, int start, int end, float x, float y, Paint paint)
public void drawText (char[] text, int index, int count, float x, float y, Paint paint)

// 第二類
public void drawPosText (String text, float[] pos, Paint paint)
public void drawPosText (char[] text, int index, int count, float[] pos, Paint paint)

// 第三類
public void drawTextOnPath (String text, Path path, float hOffset, float vOffset, Paint paint)
public void drawTextOnPath (char[] text, int index, int count, Path path, float hOffset, float vOffset, Paint paint)

Paint paint=new Paint();
 paint.setStyle(Paint.Style.FILL);
 paint.setStrokeWidth(12);
 paint.setTextSize(100);

 String text="測試：my text";
 canvas.drawText(text, 200, 400, paint);

 //畫兩條線標記位置
 paint.setStrokeWidth(4);
 paint.setColor(Color.RED);
 canvas.drawLine(0, 400, 2000, 400, paint);
 paint.setColor(Color.BLUE);
 canvas.drawLine(200, 0, 200, 2000, paint);

Paint.FontMetrics fontMetrics=paint.getFontMetrics();
 fontMetrics.top
 fontMetrics.ascent
 fontMetrics.descent
 fontMetrics.bottom

//矩形背景
 Paint bgRect=new Paint();
 bgRect.setStyle(Paint.Style.FILL);
 bgRect.setColor(Color.YELLOW);
 RectF rectF=new RectF(200, 200, 800, 600);
 canvas.drawRect(rectF, bgRect);

 Paint textPaint=new Paint();
 textPaint.setStyle(Paint.Style.FILL);
 textPaint.setStrokeWidth(8);
 textPaint.setTextSize(50);
 textPaint.setTextAlign(Paint.Align.CENTER);

 String text="測試：my text";
 //計算baseline
 Paint.FontMetrics fontMetrics=textPaint.getFontMetrics();
 float distance=(fontMetrics.bottom - fontMetrics.top)/2 - fontMetrics.bottom;
 float baseline=rectF.centerY()+distance;
 canvas.drawText(text, rectF.centerX(), baseline, textPaint);

距離 = 文字高度的一半 - 基線到文字底部的距離（也就是bottom）
 = (fontMetrics.bottom - fontMetrics.top)/2 - fontMetrics.bottom